1. Field of the Invention
This invention relates in general to a single patient use, positive oscillatory expiratory pressure respiratory therapy device which includes an air-flow bypass and, in particular, to a positive oscillatory expiratory pressure respiratory therapy device for incorporation into the expiratory limb of a ventilator circuit, and operable by a patient through passive exhalation during the expiratory cycle. The device when in an xe2x80x9conxe2x80x9d or xe2x80x9cactivexe2x80x9d mode of operation imposes an oscillatory expiratory air pressure on the patient during exhalation for the purpose of loosening secretions, and in the xe2x80x9coffxe2x80x9d or xe2x80x9cbypassxe2x80x9d mode of operation permits free flow of air through the device with minimal or no pressure drop.
2. Description of Related Art
Persons who suffer from pulmonary problems that result in large amounts of mucus being produced in the lungs often require assistance in the removal of these secretions. If these secretions are allowed to remain in the lungs, airway obstruction occurs resulting in poor oxygenation and possible pneumonia and/or death. One of the clinically recognized treatments for this condition is a technique known as positive expiratory pressure therapy or PEP. With PEP therapy, a patient exhales against a resistance to generate expiratory pressure at a substantially constant rate of flow. Prescribed expiratory pressures are generally in the range of 10-20 cm of H2O, although other pressure ranges and pressures can be used.
In the use of PEP therapy, a patient breaths through an orifice restricter to generate a positive pressure in the lungs during exhalation, with the pressure falling to zero at the end of the exhalation. By selection of the proper-sized orifice, a given pressure is determined for the exhalation flow rate generated by an individual patient. This extended, substantially constant, flow of elevated-pressure exhalation has been shown to be effective for moving secretions trapped in the lungs to the larger airways where the secretions can then be removed through coughing. It has also been found that in the treatment of patients having chronic obstructive pulmonary disease (COPD), chronic bronchitis, cystic fibrosis, atelectasis, or other conditions producing retained secretions, treatment with PEP therapy is improved by combining positive expiratory pressure therapy with airway oscillation and intermittent air-flow acceleration. To this end a hand-held, single patient use, positive expiratory pressure respiratory therapy device was developed by assignees of the present invention, and is the subject matter of a co-pending application, Ser. No. 09/449,208, filed Nov. 24, 1999 for xe2x80x9cPOSITIVE EXPIRATORY PRESSURE DEVICExe2x80x9d.
The present invention comprises a positive oscillatory expiratory pressure respiratory therapy device which is incorporated into the expiratory limb of a ventilator circuit. Accordingly, this device allows a patient on a ventilator to be subjected to positive expiratory pressure therapy combined with airway oscillation and intermittent air flow acceleration while allowing this respiratory therapy treatment to be bypassed without interruption once the ventilator circuit has been established. In this manner, all expiratory air in the ventilator circuit is accounted for, and the expiratory air volume may be accurately monitored.
As is known to respiratory therapy healthcare providers, the volume of expiratory air in a ventilator circuit is closely monitored. Once this invention has been installed into the expiratory limb of the ventilator circuit, the ventilator circuit never needs to be broken enabling the healthcare provider to accurately account for all expiratory air and maintain the integrity of the ventilator circuit. In addition, the device is constructed such that any condensation forming in the device will drain out from the housing because of the interior design which facilitates the flow of condensate out from the device into the ventilator circuit. Furthermore, the transparency of the housing permits inspection of the interior to insure that condensate is not being retained in the device.
As is also known to respiratory healthcare providers, the use of an oscillatory expiratory pressure imposed on the patient must be carefully controlled. To this end, a ventilator circuit includes apparatus to closely monitor the positive end expiratory pressure (PEEP). Accordingly, the amount of expiratory air pressure buildup in the opening pressure cycle for producing the airway oscillation, and intermittent air flow acceleration, must be carefully controlled. To this end, during the xe2x80x9conxe2x80x9d cycle or xe2x80x9cactivexe2x80x9d mode of operation, the present invention is designed such that oscillatory expiration occurs throughout the entire expiratory air cycle until the expiratory air pressure decreases to the point where oscillation can no longer occur, but never exceeds the allowable PEEP.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the relevant technology. As will be more readily understood and fully appreciated from the following detailed description of a preferred embodiment, the present invention is embodied in a positive oscillatory expiratory pressure respiratory therapy device for incorporation into a ventilator circuit. The device includes a bypass for selectively directing the expiratory air discharged from a patient through the device for oscillatory PEP treatment or bypassing the device to discharge the patient""s expiratory air directly through the ventilator circuit. In this manner, once the device is installed into a ventilator circuit, the integrity of the ventilator circuit always remains intact and the patient expiratory air volume may be accurately monitored.